Railway-traffic-controlling apparatus



Dec. 16, 1930.

v H. A. THOMPSON RAILWAY TRAFFIC CONTRbLLING APPARATUS 9 Sheets-Sheet lINVENTOR H. A Thlornpsan,

Fi led Nov. 5. 1.927

.w i f Wham Dec. 16, 1930. H. A. THOMPSON RAILWAY TRAFFIC CONTROLLINGAPPARATUS Filed Nov. 5, 1927 9 Sheets-Sheet 2 INVENTORZ H. h Thompson OZZT Dec. 16, 1930. H. A. THOMPSON RAILWAY TRAFFIC CONTROLLING APPARATUSFiled Nov. 5, 1927 Q-Sheets-Shee'tl 5 INVENTOR AJThU-h-psm Dec. 16,1930.. THQMPSON I 1,784,851

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Nov. 5, 1927 9 Sheets-Sheet4 INVENTOR. HJ). Th amps on 51' QM a Dec. 16, 1930.

H. A. THOMPSON RAILWAY TRAFFIC CONTROLLING APPARATUS File; Nov. 5, 19279 Sheets-Sheet 5 Q'R'W M W INVENTOR. H. A- Thompson Dec. 16, 1930. H. A.THOMPSON RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Nov. 5. 1927 9Sheets-Sheet 6 Z A? $3 3 a R wk U p NH 4 b A m E J b J m N 3 111K WKN 7w w%\ 8% R Q AN m 1 X 5% b QNV R N Q Dec. 16, 1930. I

H. A. THOMPSON RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Nov.. 5, 19279 Sheets-Sheet '7 INVENTOR'. H A Th arm Dec. 16,1930.

H. A. THOMPSQN RAILWAY TRAFFIC CONTROLLING APPARATUS 9 Sheets-8heet 8 II Filed Nov. 5, 1927 INVENTOR J H. [a Thompson,

Dec. 16, 1930. H. A. THOMPSON 1,784,851

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Nov. 5, 1927 9 Sheets Sheet9 m n/t H. .Thom -son,

(2- 6mm. 2k

* to winding 5 of the relay Patented Dec. 16, 1930 ouiren sures PATENTOFFICE HOWARD A. THOMPSON, OF EDGEVVOOD. PENNSYLVANIA, ASSIGNOR TO THEUNION SWITCH & SIGNAL COMPANY, OF S'WISSVALE, PENNSYLVANIA, ACORPORATION OF PENNSYLVANIA RAILWAY-TRAFFIC-CONTROLLING APPARATUSApplication filed. November 5, .1927. SerialNo; 231,277.

My invention relates to railway trafiic controlling apparatus, andpartlcularly to apparatus for controlling highway crossing signals, thatis, signals which are placed adjacent intersections of highways and railways for the purpose of warning users of the highway when a trainisapproaching the intersection.

I will descrlbe several Iorms of apparatus embodying my invention andwill then point out the novel features thereof in claims.

in the accompanying drawings, Figs. 1 and 2 when placed end to end withFig. 1 on the left, constitutea view showing one form of railway trailiccontrolling apparatus embodying my invention. Figs.- 3-9, inclusive, areViews showing a number of modifications ofthe apparatus illustrated inFig. 2.

Similar referencecharacters refer to similar parts in each of theseveral views.

Referring first to Figsl and 2, the refer ence characters 1 andladesignate the track rails of a stretch of railway track over whichtral'licnormally moves inthe dlrectlon 1nd1- cated by the arrows- Theserails are divided,

2, into a pluby means of insulatedjoints rality of successive tracksections A-D,

. D-G, etc. Track circuit current is supplied to the rails of eachsection from a track transformer designated by the reference character Twith asuitableexponent and having its secondary connected across the,rails adjacent the entrance end of the corresponding section. Theprimary of each .trackti'ansformer T is constantly supplied withalternating current from terminals :0 andg of a suitable source ofenergy not shown in the drawing. Each track section is also providedwith track relay designated by'the reference character R with a'suitableGKPO- nent and comprising .t-wowindings 5 and 6, one of whicln5, isconstantly connected across the rails adjacent the exit end of-thecorresponding section. The other winding 6 of each track relay isconstantly supplied with alternating current from terminals m and y sot-h when track circuit current is supplied from the rails of thecorresponding section, the track relay becomes energized. i 2 Each tracksection is further provlded with a, repeater relay designated by thereference 5 character P with an appropriate exponent and locatedadjacent the entrance end of the section. Referring particularly torepeater relay P this relay is provided with a circuit which may betraced from terminal :0, through front contact 7 of track relay R, Wires8 and 9, and winding of relay P to terminal y. Relay P? is thereforeenergized only when track relay R is energized. Re-

lay P is controlled by track'relay R in the trol of traffic alonghighways N andN re spectively. An insulated joint 2 is located in raililof; section A-D across this joint in series cuit of section A'-D. Asecond winding of relay Q is constantlysupplied with alternating'currentfrom terininalsac and ,y in such manner that the relayis'normally en-'ergized, bythetrack circuit current which flows through winding? of therelay when the section AD is unoccupied. In similar with the track cirmanner, winding 3 of relay Q is connected across a second insulated.joint 2? in rail 1 of section A Dand windings 3 of relays Q and Q areconnected across insulated joints 2 'and 2 in rail 1'? of section D Gadjacent points E'and F,'respectively. The remaining winding 4 of eachof the relays QQQ and Q? isco-nstantly supplied with alternatingjcurrentfrom terminals a: and y in such manner that the relays Q arejallnormally energizedby the track circuit current supplied to theassociated section. The crossing point B in the adjacent point B, c andone winding 3 of a relay Q 18 connected signal H is controlled directlyby relay Q so that when this relay is de-energized current is suppliedfrom terminals as and 3 to the operating mechanism of the signal overback contact 17 of relay 6),. The signal 131 is therefore operatedwhenever relay Q is deenergized.

Signal H iscontrolled by a relay L so that when this relay isale-energized to close its back contact 22, signal H is operated.Furthermore, a relay L Controls signal H so that when back contact 30 ofrelay L is closed, relay H is operated' Relay L jis controlled by relayQ and by a relay J which is in turn controlled by relay Q The referencecharacter T designates a transformer having its primary connected inparallel with relay P so that this transformer is supplied with currentwhen relay R is energized. When relay Q is energized, the secondary oftransformer r is connected over front contacts 15 and 16 of relay Q}?with the winding of relayJ through a rectifier'50, and relay J istherefore energize-d. When relay Q is de-energized, the winding of relayJ is connected through rectifier 50 and back contacts 15 and 16 with thesecond ary of a transformer t which has its primary constantly connectedin parallel with Winding 3 of relay Q". When relay Q is deenergiz-ed,therefore, relay J is energized only if an alternating difference ofpotential is suppliedacross the insulated joint 2 and when relay QPisenergized, relay J 'is' energized only if relay R is also energized. WVhen relay J is energized and when relay Q is also energized, currentflows from terminal :0, over front contact 18of relay J wire19, frontcontact 20 of relay Q wire 21, and winding of relay L to terminal y,thereby energizing relay L and holding its back contact 22 open toprevent operation of the signal H3, 7 p i p I V The control of relay J Eby relay Q} and by transformers 23 and T is similar to the control ofrelay J by relay Q and transformers pick-up circuit which may betracedfrom terminal is, through front contact 23 of relay Q wires 24 and 25and winding ofrelay L toterminal '1. Relay L is also provided with astick circuit which'may be traced from terminal 50, through frontcontact 26 of'relay J wire 27, front contact 28' of relay L wires 29 and25, and winding of relay Ll to terminal y. Relay L therefore, rbecomesenergized whenever relayQ- becomes energized, and is subsequentlymaintained in its energized condition as long as relay :J ree mainsenergized.

The apparatus is intended for co-operation with'traincarried governingmeans responsive to train controlling current supplied to the trackwayfrom herein shown and described a point in advance of the train. For thepurpose of supplying this train controlling current to the trackway,each track section is provided with a coding device designated ingeneral by the reference character K with a suitable distinguishingexponent and each comprising a motor 31 and two code wheels 32 and 33operated thereby and each provided at itsperiphery with a plurality ofteeth, The code wheel 32 co-operates with a movable contact 34 to movethe contact alternately into engagement with two fixed contacts 34 and34" when thecode wheel is rotated. In similar manner when code wheel 33is rotated a movable-contact-member 35 is'moved alternately intoengagement with two fixed contacts 35 and 35. It will be observed fromthe drawing that the code wheels '32 and 33 have different numbers ofteeth so that when the device K is operated the contact members 34 and35 are actuated at different frequencies.

' Train controlling current is supplied to section D-G by the codingdevice K through a train control transformer designated in the drawingby the reference character S and having a secondary 10 connected acrossthe rails in series with the winding 5 of track relay R Under normalconditions, that is, when relay R- is energized, the primary 11 oftransformer S is short-circuited, through a path of low resistance whichmay be traced from the right-handterminal of primary 11,

through wire 36, front contact 37 of relay R and wires 38 and 39 back tothe left-hand terminal of primary 11. Under these conditions theimpedance of secondary 10 is comparatively small and does not interferewith the proper operation of relay R by track circuit current suppliedthereto from transformer T at the opposite end ofthesection. WVhenrrelayR is de-energized, however, the path of low resistance just traced forprimary 11 of transformer S is interrupted. A circuit is now closed formotor 31 oft-he coding device K from terminal'X, overback contact 7 ofrelay R wires 40 and 41 and motor 31 of coding device K to terminal y.The motor 31 of the coding device K is therefore operated to actuate thecontact members 34 and 35 as explained hereinbefore. Assuming that relayP is energized, each time contact 35 is moved 'to the right, currentfiows'from terminal 00,

through back contact 7 of relay R3, wires 40, p

42 and 43, contact 35- 35, wire 44, front contact 45 of relay P wires 51and 36, primary 11 of transformer S, wires 39, 46 and 47, im-

- ity of the train controlling current.

Returning now to the. operation of the coding device K when contact 35next moves. to the left, the circuittraced for supplying energy toprimary 11 of transformer S is interrupted and a path of low resistanceis closed for this primary from the righthand terminal of the primary,through wires 86 and 51, front contact 45 of relay P wire 44, contact35-35 and wires- 47, 46 and 39, back to primary 11 of transformer SDuring the interval of time that the circuit just traced is closed, theprimary 11 of transformer S is short-circuited sothat the impedance ofsecondary 10 of this transformer is comparatively small. If, under theseconditions, the section D-G is unoccupied,- so that current fromtransformer T may reachthe winding of relay R ,this relay will becomeenergized. The reference character 12 designates a reactor which isconnected directly across windingb of relay R and which has thecharacteristic of increasing its impedance in response to decreases inthe electromotive force applied thereto. For example, thisdevicemay be aleakage reactor of the usual and well known construction. With thisarrangement the impedance of the reactor 12 has the effect of shuntingcurrent away from windingfi of relay G which effect is comparativelysmall for the low values of electromo tive force appliedflto the reactorby trans former T E-but when train controllingcun rent is being suppliedthe rails by transformer S a comparatively high electrometive force isapplied across the terminals of reactor 12- andfits impedance is thencorrespondingly low; thereby increasing its tendency to shunt currentaway from winding 5 or relay B. As a result a relativelysma'llproportion of train controlling currents flows through winding 5 ofrelay R". V i

' \Vhen relay l? is ole-energized, the circuits for transformer S aresimilar to those just traced, except that contact 34 .3l"is substitutedfor contact 85-35 and contact iii-3 is substituted for contact 353F Itfollows that when relay R is de-energized, train con.- trolling currentis supplied tot-he railsof. sec tion D-G and. this, train controllingcurrent is periodically interrupted atfa comparatively high frequency ifrelayP is energized and at r acomparativelylow frequency if this relayisqdeenerlgizedp The train carriedi gover able manner.

ing means'may be selectively responsive to the frequencies of theperiodic interruptions in the train controlling current in any suit- ,Asshown in the drawing the stretch of track is unoccupied so that all ofthe track relays It and all of the relays Q are energized. Relays l?arealso energized. its a result, the coding devices K are all at restand no train controlling currentis supplied to the rails. Relays J F7, Land L are also energized and the circuits for all of the highway signalsl H and l-lfare open.

In explaining the operation of the apparatus, I will assume that a trainmoving in the direction of the arrow traverses the stretch of trackshown in the drawing. When this train enters section AD, the shuntingeffect of its wheels and axles decreases the track circuit currentflowing through the track circuit of the section. Relays Q Q and Rtherefore become ale-energized. The closing of back contact 17 relay QPcompletes the circuit for signal H which thereupon commences to operate.The closing of back contact 7 of relayR sets. motor '31-of coding deviceK into operation and, assumingthat relay P is energized, traincontrolling current isintermittently supplied to transformer S overcon.- tact 35 operated by code wheel 33. Relay Q is now de energized sothat relay J C is connected through rectifier 50 with transformer t Eachimpulse of traincont-rolling current supplied to the railscauses acorresponding impulse of energy to be supplied through transformer andrectifier 50 to relay J Due to the slow acting characteristics of thisrelay, it holds its front contacts closed during the time intervalbetween successive impulses of the train controlling current and during7 the transfer of energy from transformer r to 15. Front Contact 18 ofrelay J therefore remains closed and relay L is held in its energizedposition to prevent operation of the signal H When the train hascompletely passed point Bftrack circuit current from transformer T flowsfrom rail 1, through the Wheels and axles of the train to rail 1 on theright of in sulated joint 2 and return through passed point current fromtransformer T picks up relay Q thereby connecting relay J? withtransformer 1. But the primary cir-,

. cuit'of this transformer isnow' open at back contact 7 of relayRPso'that relay J becomes :e-enr-z'rgized; The opening offront contactl8 of'this'relay interrupts the circuit for re at L and the latterrelay-opens to set signal p When the tra n enters sect1on-D-G,= relays QQ and It become H iinto operation.

de-energized, and relay P also becomes deenergized. Train controllingcurrent is now being supplied to the railsofsectlon DG throughtransformer-S but for the reasons already explained, this traincontrolling current does not energize relays QP, Q and RG.

Relay J E now receives train controlling cur-.

impedance of secondary of this trans former the track circuit currentpicks up relay R thereby de-energizin device K and discontinuingthesupply of train controlling current from the rails of section A-D.When front contact 7 of relay R- closes, current is supplied to relay Pand to the primary of transformer r and since relay J is connected withthis transformer relay J now becomes energized. The closing of contact18 of relayJ does not energize relay L however, because the circuit forrelayL is now open at front contact 20 of relay Q, and the signal Hcontinues to operate. lVhen the train passes point E, train controllingcurrent from transformer T flows through winding 3 of relay Q and picksup this relay.- This operation completes the circuit for relay L andopens back contact 22 thereon to discontinue the opera 4 tion of signalH Relay J is now connected with the secondary of transformer a but theprimarycircuit for this transformer is open at front contact.7 of relayR and relay J becomes de-energized. The pick-up circuit for relay L wasopened at front contact 23 of relay Q when the train first enteredsection DG and the opening of front contact 26 of relay J breaks thestick circuit for relay L which thereupon closes its, back contact 30and sets signal VH into operation.

lVhen the train passes point F, relay Q- becomes energized, therebyclosing the pick-up circuit for relay L and breaking the oper: atingcircuit for signal H at back contact 30 of relay L When the train passesout of section DG, relay R becomes energ1zed, thereby interrupting thesupply of train con trolling current to the rails of sectionDG- andsupplying energy torelay P and to transformer r Relay J thereforebecomes energized to complete the stick circuit for relayL and torestore the apparatus to its normal condition.

Referring now to Fig; 3,; the apparatus is similar to that shown in Fig.2, but one winding52 ofa transformer M is connected inse-' ondary 10 ofthe train control transformer S is connected in parallel with winding 5.=1 and'winding 52 in series. \Vith thisarrange the coding ment it willbe apparent that if the polarity of the train controlling current issuch as to hold the relays Q and Q in their de-energized position withthe train between points D and'E, the train controlling current willflow throughwinding 5 of relay H in the same instantaneous direction asdoes the track circuit current from transformer T when section DGr isunoccupied. If winding 6 of relay R 'were constantly supplied withalternating currentof a single relative polarity as in Fig. 2, thisrelay would be energized by train controlling'current supplied to therails by transformer S. In order to prevent this, I control the relativepolarity of the current supplied to winding 6 of relay R overpole-changing contacts 54 and 5 8'on relay Q Under normal conditions,-when section -DG is unoccupied, currentfiows from terminal a: over frontcontact 54 of'relay Q wire 55, winding 6 of relayR ywires 56 and 57,front contact 58 of relay Q to terminal 3 Under these conditions thepolarity of the current in winding 6 is such that relay R is energizedby track circuit current supplied to winding 5 bytransformer T When atrain enters sectionD-G, thereby de-energizing relays QP, Q and Rcurrent flows from terminal as over back contact 54 of relay Q wires 57and 56', winding 6 of relay R wire 55,and back contact 58 of relay Q toterminal y. Under' these conditions, the relative instantaneousdirection of the current in winding 6 is reversed with respect to thedirection of the current supplied to the winding when relay Q is closed;The deenergizationof relay R closes back' contact 60, whereupon currentflows from terminal as over back contact 54 of relay Q wires 57 and 59,back contact 60 of relay R wires 61 and 62, motor 31 of coding device Kwires 125, 66, and 55, and back contact '58 of relay Q to terminal 3 Themotor 31 is therefore operated and if relay P is energized a circuit nalWhen this circuit is closed, train controlling current is supplied tothe rails of section DGr from transformer S and the polarity of thiscurrent is such that it flows through windings 3 of relays 'Q and Q inthe opposite direction from the direction in which, track circuitcurrent from transformer T flows through these windings.

V Since winding :10 is connected in parallel ries with'winding 5- ofrelay R ,-and the secv train controlling current flows through windwithwinding.v 5 of relayR however,the

ing 5 in the same direction as the track circuit with Fig. 2 and the pole-changing contacts,

54 and 58 thereupon reverse the polarity of the current supplied toprimary 11 of transformer S At the sametime, however, the polarity ofthe current supplied to winding '6 of relay R is also reversed'so thatthis relay remains in lllS'Cl-GIIGIgiZCl position. .It will be observedthat wlnding 53 of transformer M is shunted by front contact 3'? ofrelay when this relay is energized. The winding 53 is also shunted eachtime thecontact 34 or 35 of coding device K which is in circuit" withprimary 11 of transformer S is closed,1

in the same manner as primary 11 offtransformer S is shunted in F 1g. 2.When the train passes out of the section, assuming re-j lay P to beclosed, during the next interval that contact3535 is closed, currentfrom transformer T flows through winding 5 of relay R and due to thesmall impedance of winding 52 of transformer M which results fronitheshort circuit placed upon winding 53 of this transformer, sufficientcurrent is supplied to windingj5 to energize relay R In all otherrespects the operationof the apparatus illustrated in Fig. 3 is similarto that described in connection with Fig. 2.

In the modification illustrated in Fig. 4:, the train controllingcurrent is supplied to the trackway by secondary10'of transformer Sconnected in parallel with winding 5 of.

relay R and winding 52 of transformer M The circuits for transformers Mand S are similar to the circuits for slmilar parts in Fig. 3 exceptthat the circuit for S in'Fi iet' does not include pole-changingcontacts on relay Q but the polarity of the current supplied bytransformer S is such that the current supplied to winding 5 holds therelay open. The current then supplied to' therails of the sectionis ofsuch polarity as to flow through the relays Q and QPin the samedirection astrack circuit current supplied by relay T It will beobserved, however, that in this modification, the section D'G isdividedinto a forward'sub-section F,G and a rear subsection DF. Rail 1 ofsub-section D-F is connected through winding 3 of relay Q), with rail 1or 1 of sub-sectionFe-G ac cording as relay Q3 is closed or open, andrail 1 of sub-section DF is connected directly with rail 1 or 1 ofsub-section FG accord ing as relay Q is closed or open. It will beplain,therefore that the contacts 67 and 68 .of relay Q constitute apole-changer for reversing the polarity of the traincontrolling currentsupplied to the rails inrear of point F. Due to the insertion of winding3 of relay Q? in the connections between the rails of the sub-sectionsD-F and F--G,the direction of the current through this winding whentrain controlling current is being supplied to the section and atrain islocated in the sub-section D-F, is such that relay Q -is held open. Withthis arrangement relay Q is normally energized by trackcircuit currentbut when a train enters the s'ection DG this relay becomes'de-energized, therebyreversing the connections between the rails ofsub-sections D-F and F-eG. At the same time, train controlling currentis supplied to theitransformer S as will be apparent from the drawing. With relay Q) down this train controlling current flows through winding 3of relay in such direction as to hold the relay open. Furthermore, therelative polars ity of the current now suppliedto winding3 of relay Qfr'om transformer S is such that. relay Q is also held in itsde-energized posi-' tion. When the-train passes point E, relay Q becomesenergizedbytrack circuit current supplied by transformer T as explainedhereinafter and when'the train passes point F, the track circuit currentflowing from transformer T reverses the, direction of the current inwinding 3 of relay [CF and picks up this relay. After, relay Q hasclosed, the

direction of the currenti'n winding 3 is still 1 such as to hold therelay closed. Thecontrol of the highway crossing signals by therelays. Qand Q? is the same as has already been described in connection with'Fig.2.

In the modification shown in Fig. 5, winding 5 of relay R, is normallyconnected with the rails over its own front'contact 74, the circuit forthis winding passing from rail 1, through wires 70 and 71, winding 50frelay; R wires 72 and 73, front contact 74 of relay R and wires 7 5 and76 back to rail 1?. The secondary of the train control transformer S isconnected directly across the rails so that Y when the circuit justtraced is closed, wind ing 5 is connected in parallel with secondary 10of transformer S The train controlllng current suppliedby transformer Sis of such polarity as to hold relays and Q closed. It will be apparentthat if winding 5 of relay R is'o'onnected with the rails when traincontrolling current is being suppliedto the trackway the relay will beenergized by s'uch train J cont-rolling current. When a trainenters thesection D' G, however,de-energizing relay R the circuitjust traced forwinding. 5 is opened, thereby disconnecting the winding from the rails.The de-energization of relay R also sets the coding device K intooperation. In the form here shown, this coding device is provided with acontact 6868 operated by code wheel 32, and arranged to be closed whencontact 3 34! is open. In simi- ;lar manner code wheel 33 operatesacontact 69,69 arran ed to be closed when contact 3535 is open.A-ssuming'that relay P is energized, train controlling current 1s sup-'plied to the primary of-transformer s each relay, P wire 51, backcontact77 of relay R wire 78, and primary 11 of transformer S to terminal 3 Thecurrent thus supplied to the. trackway from the train control trans.-former S flows through the rails in such direction as to hold relays Qand Q in their de-nergized positions, and this current does not energizerelay R because winding 5 is disconnected from the track rails. Duringthe interval between successiveimpulses of train controlling current thewinding 5 of relay R is connected with the rails over a circuit whichmay be traced from rail 1, through wires and 71, winding 5 of relay Rwires 7 2 and 82, front contact 81 of relay P wire 80, contact 6969,wires 150 and 7 9, back contact 74 of relay R and wires 7 5 and 76, torail 1. After a train passes outof section D-G, therefore, the relay Rbecomes energized during the next succeeding interval between impulsesof train controlling current, thereby de-energizing the coding device Kand restoring the apparatus to its normal position in which the winding5 of relay R isconnectedacross the track rails through its own frontcontact 74. The operation of the highway crossing signals in Fig. 5 willbe readily understood from the explanation of the preceding figures.

Under some conditions of operation, it may be desirable to operateahighway crossing signal, such for example, as signal H to protect trainmovements in either direction. This may be accomplished with theapparatus shown in Fig. 6.. In the modification here shown, the relay Rmay be controlled in accordance with any of the schemes illustrated 1nFigs. 2, 3, 4 or 5 so that this relay is deenergized when the section isoccupied by a train moving in either direction and is energized when thesection is unoccupied. The relay R controls apparatus for supplyingtrain controlling current to the track rails in the same manner as inthe preceding views.

Associated with relay J E is an interlocking re-,

lay 17 comprising two windings U and U. When either of the back contacts92 or 93 of relay U is closed, current is supplied to the signal H tooperate this signal. The circuit for winding U of relay U is similar tothe circuit for relay L in Figs. 25, inclusive, and passes from terminalas on Fig. 1, through frontcontact 18 of relay J wire 19, front contact20 of relay Q wire 21, and winding U to terminal 1 The circuit forwinding U passes from terminal w, over front con- J wire 84, and windingU tact 83 of relay to terminal 3 Winding 4 of relay Q is normally sup-;plied with energy from terminal so, over front contact 85 of relay Qwires 86 and 87,

winding 4 of relay Q? to terminal This winding is provided with twoother circuits, one of which passes from terminal a over front contact88 of relay R wires 89, 90 and 87,winding 4 of relay to terminal 3 andthe other of which passes from terminal. a", over back contact 83 ofrelay J,

wires 91, 90 and 87, and winding 4 of relay Q to terminal 1 It should beobserved that the primary of transformer is'connected across the rails 1and 1 of section D-G on the right-hand side of the insulated joint 2.With the apparatus shown in this view when a train passes point C inFig. 1, the de-energization of relay J 0 opens the circuit for winding Uof the interlocking relay U.

The closing of back contact 92 therefore sets the crossing signal H intooperation. When the train proceeds into section D-G, relay R becomesenergized, thereby opening front contact 88. Relay QP also becomesde-ener-- gized, thereby connecting relay J E with transformer :9 Thistransformer now receives energy from the train controlling currentsupplied to the exit end of the section under the control of relay RRelay J E is therefore energized and. back contact 83 of relay J isopen. It will be plain therefore that all of the circuits for winding .4of relay Q are open and winding 4 is therefore deprived of energy. Whenthe train passes point E, the shunting effect of the train discontinuesthe supply of the train controlling energy to transformer 25 and relay JE therefore opens. Winding. U of the interlocking relay U is nowtie-energized, but due to the interlocking features of the relay,

back contact 93 does not close. Back con-,

tact 92 of relayU remains closed, however, and the signal H continues tooperate. When the rear of the train passes point E, train controllingcurrent flows through winding 3 of relay 'QP. Since relay J is nowde-energized, current is supplied to the winding 4 of relay Q over backcontact 83 ofrelay J E and relay Q? picks up. Relay J became energizedwhen the train passed out of section AD and the energization of relay Qtherefore completes the circuit for winding U of relayU,but back contact93 of relay U remains open. The operating circuit for signal H istherefore opened andthe oper-- ation of the signalis discontinued. Vhenthe train passed out of the section DG thev front contact 7 on thisrelay breaks the circuit for transformer 7 and since relay Q .isenergized by'track circuit current from transformer T9, relay J becomesde-energized. Winding U ofrelay U is therefore de-energized and backcontact 93 closes to set signal H into operation. When the front of thetrain passes point E, relay Q drops,

and the circuit for winding U of relay U is then opened, but contact 92of this reset signal H into operation as the trainapproaches the signalandwill discontinue the operation of thesignalafter the rear of thetrain has passed point E.

In some of the modifications hereinbefore disclosed the traincontrolling current supplied to'the rails forces the relays QP, Q? and Rinto their de-energized positions. With some types of relay, thisoperation may be undesirable and with the circuits shown in Fig. 7instead of reversing the direction of operation of the relay, Idisconnect the supply of energy to one winding of the relays QP, Q or Hwhen train controlling current is being suppliedto the trackway, so'thatit is impossible for such train controlling current to energize theserelays.

Referring to Fig. 7 ,winding 4 of relay Q is normally supplied withcurrent over its own front contact 101, and in similar manner Winding 4of relay Q? is normally supplied 7 With current over its ownfrontcontact 98 plied with, current over its own front contact 94. Whena train enters section D'G,

however, relays QP, Q and RPbecomes deenergized and the circuits justtraced for supplyingwindings 4 of relays Q? and Q? and winding 6 ofrelay'R T become open. The closing of back contact? of relay R sets thecoding-device K into operation, and assuming that relay P is energized,-train control ling CUYIGIIUIS supplied to primary 11 of transformer Seach time contact 3535 is closed over-a circuit which passes fromterminal 00, through back contact 7 of relay R Wires 40 and 103,frontcontact 104 of relay P wire 105, contact 35- 35 wires 106, 151 and 107,primary 11- of transformer S and Wires 108 and 109, to terminal y. Thesecondary of transformer S is connected in series with winding 5 ofrelay H in thesame manner as in Fig. 2. The train controlling currentthus supplied to the trackway cannot energize relays QRQ or B becauseeach of these relays has its winding 4 open-cin cuited. Whencontact 3535of coding device K is closed, current flows from terminal at, throughback contact 7 of relay R wires 40 and 103, front contact 104 of rela IP wire 105, contact 35-35, wires 110 and 111, back contact 94 of relay RWires 95 and 96,-winding 6 of relay H to terminal 3 During the intervalbetween successive impulsesof train controlling current, winding 6istherefore energized so thatif under these conditions, track circuitcurrent is supplied to winding 5, relay R will become energized.

The closing of contact 35'3 t" also supplies current to winding 4 ofrelay Q over a branch for the circuit just traced which passes from-wire95,=through wire 97,"back contact 98 of relay Q wire 99, winding 4 ofrelay Q? to terminal y. passes from wire 99, through wire 100, backcontact 101 of relayQ wire 102, and wind ing 4 of relay Q to'terminal Itwill be plain, therefore that while the supply of current to one windingof each of the relays QP, Q and R is interrupted during the impulse oftrain controlling current, these windings are suppliedwith energy duringthe inter- Vals between such impulses so that during these intervals therelays can be-energiZed-by I track circuit current. It should also'be observed that durlng the interval between successive impulses of tramcont-rolling current supplied to the-trackway, a circuit of lowresistance is closed for primary 11 of transformer S which may be tracedfrom the lefthand terminal of this primary through wires 107 and 151,contact 69-69 ofcoding device K wire 112, front contact 113 of relay Dand Wires 114 and 108, back to the right-hand terminal of this primary.The consequent reduction in the impedance of secondary 10 V oftransformer S during the intervals beand winding 6 of relay R isnormally suptween successive-impulses of train controh ling currentfacilitates the energization of relay R by track circuit current fromtransformer T Returning now to the apparatus illustrated the primary oftransformer F is connected in Another branch parallel with winding 3 ofrelay (JP and the secondary of transformer 6 is connected with the relayJ over back contacts of relay so that re primary of transformer Z'operates hint of low resistance in parallel with is removed with theapparai'iged as shown in Fig. 8 in which the primary oftransformer 'tisconnected across rails 1 and of the section DG on the right of theinsulated joint With this arrangement when the trainynusses the joint 2relay J becomes (lo-energized as before, but when the transformer isconnected in this manner there is no tendency to shunt the winding 3 of3 of relay This undes rable pos ratus arrelay J Fig. 8 also diflers fromFig. 2 in that current is normally supplied to winding 4 of relay Q overfront contact 101 of the relay. Nhen the relay becomes de-energized,this circuit is of course opened but when relay J drops, current issupplied to winding 4: over back contact 83 of relay J When the trainpasses point E, (ls-energizing relay J current is restored to winding atof relay J so that-after .the rear of the train clears the joint W, therelay Q may become energized by track circuit current from transformer TIf a train enters section; DG thereby deenergizing relay Q and thenbacks out of the section without tie-energizing relay J both of thecircuits already traced for winding 4 of relay Q will be open. As soonas this train backs out of the section, relay R will pick up asexplained in connection with Fig. 2 and a circuit will be closed fromterminal 00, over front contact 7 of relay R wires 8, 116, 117 and 118,back contact 101 of relay QP, wire 102, winding 4 of relay Q to terminal2 \Vhen this circuit is closed, track circuit current from transformer Tflowing through winding 3 picks up relay Q. A slow-acting relay J Fsimilar to relay J E is associated with relay Q for supplying current towinding 4 two insulated joints 2"v and 2 1 are located in the rails 1and 1*, respectively adjacent point F and the rails outside of thesejoints are connected together by a conductor 122. Winding 3 of relay Qis connected across the rails between the joints 2 and 2 1. With thisarrangement relay Q will be shunted until the train has cleared joint 2and current will be shunted away from transformer F to open relay'J assoon as the train passes joint 2 The purpose of this arrangement is toinsure that the relay J becomes de-energized before the train shunt isremoved from relay Q thereby insuring that relay Q will be properlypicked up. In similar manner, relay QF is shunted until the train haspassed joint 2 but relay J F is shunted as soon as the train passesjoint 2}.

Although I have herein shown and described only a few forms of railwaytrafi'ic controlling apparatus embodying my invention, it is understoodthat various changes and modifications may be made therein within thescope of the appended claims without departing from the spirit and scopeof my invention.

Having thus described my invention, what I claim is: I

1. In combination, a section of'railway track, a highway crossing saidsection, a

source ofenergy connected across the rails 2. In combination, asectionof' railway track, a source of energy connected across the railsadjacent one end of the section, two in--- sulated joints in one raillocated at spaced points intermediate the ends of such section,

two windings one connected across each said joint, and a-trackway signalcontrolled by said windings.

3. In combination, a section 'of railway track, an insulated joint inone rail, a winding connected across said joint, means for normallysupplying the track rails in series with current of one relativepolarity, means for at times supplying the'rails in series with currentof the other relative polarity, and a trackway signal controlled by saidwinding in accordance with the relative polarity of the current suppliedthereto.

4.. In combination, a section of railway track, means for supplyingtrack circuit current to the rails adjacent the entrance end of thesection, means effective when the section is occupied by a train tosupply train'controlling current to the rails adj acent'the exit end ofthe. section, an insulated joint in one rail of the section, a relayconnected across said joint and arranged to be energized by such trackcircuit current but not by such train controlling current, and a signalcontrolled by said relay.

5. In combination, a section of railway.

track, means for supplying track circuit current to the rails adjacentthe entrance end of the section, means efiective when the section isoccupied by a train to supply train controlling current to the railsadjacent the exit end of the section, an insulated joint in one rail ofthe section, a relay connected across said joint and arranged to beenergized by such track circuit current but not'by such traincontrolling current, a second relay, means controlled by the first relayfor at times supplying the second relay with energy in parallel with thefirst relay, and a signal controlled by the second relay.

6. In combination, a section of railway track, means for supplying trackcircuit curexit end of the section, a first relay connected across therails adjacent the exit end of the section and arranged to be energizedby V with energy when the first relay is energized,

a second transformer supplied with energy in parallel with said secondrelay, and a third relay connected with the first or the secondtransformer according as the second relay is energizedor de-energized.

7 In combination, a section of railway track, means for constantlysupplying current of one relative polarity to the rails adacent one endof the section, means effective when the'section is occupied by a trainto sup ply current of the opposite relative polarity to the railsadjacent the other end of the section, an insulated joint in one rail ofthe section, a relay comprising a first winding constantly supplied withcurrent and a second I winding connected across said joint in suchmanner that the relay is energized by current of such one'relativepolarity but not by current of the other relative polarity, and a signalcontrolled by said relay.

8. In combination, a section of railway track, means for constantlysupplying current of one relative polarity to the rails adjacent one endof the section, a track relay having one winding connected across therails adjacent the other end of the section, means effective when saidtrack relay is dc energized to supply current of the opposite relativepolarity to the rails-in parallel with said one winding whereby such onewinding is supplied with current of said one relative polarity, aninsulated joint in one rail of the section, a second relay having awinding connected across said joint and responsive to the relativepolarity of the current supplied thereto, a second winding on said trackrelay, and means for supplying said second-wind ing with current ofonerelative polarity or the other according assaid second relay isenergized or de-energized. i

9. In combination, a section of railway track, means for constantlysupplying cur rent to the rails adjacent one end of the section, aninsulated joint in one railof the section, a relay having one windingconnected across said joint and a secondv wind ing supplied withcurrent, and a signalcontrolled by said relay. 10. In combination, asection of railway track, means for constantly supplyingrcurrent of onerelative polarity to the rails adj acent one end of the section, meansfor at times supplying current of the other relative constantly suppliedwith currentof a single 11. In combination, a section of railwaytrack,'means for at times supplying periodically varied alternatingcurrent to the rails adj acentone end of thesection, an insulated jointin one rail of the section, a transformer having a primary connectedacross said'joint, a slow acting relay, means including a rectifier forsupplying energy from thesecondary of said transformer to said relay,and a signal Y controlled by said relay.

12. In combination, a section of railway track, an insulated joint inone rail of the section. a winding connected across said joint, meansfor supplying alternating current to the rails adjacent one end of thesection, and means controlled by said winding for at times periodicallyvarying said current.

In testimony whereof I affix my signature.

' HOWARD A. THOMPSON.

